• Korean Journal of Weed Science
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• v.18 no.3
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• pp.179-185
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• 1998

This study was conducted to investigate changes in weed occurrence and dominance as affected by seeding dates in water seeded rice paddy under field following two years of no-tillage condition. The pre-emergence weeds in no-tillage paddy were controlled by glyphosate application at 7 days before seeding. The rice seeds were seeded on April 20, May 10 and May 30, respectively with 40kg/ha of seeding rate. The weed species in the paddy occurred included three species (Echinochloa cursgalli, Aneilma keisak, Ottelia alismoides) of annual weed, one species (Alopecurus aequalis) of biennial weed and five species (Eleocharis kuroguwai, Leersia japonica, Sagittaria pygmaea, Sagittaria trifolia, Potamogeton distinctus) of perennial weed respectively. Aneilma keisak was found to be dorminant on April 20 and May 10 but Eleocharis kuroguwai on May 30 based on number of weeds. The number and dry weight of weeds occurred were higher on May 10 as compared to in other seeding dates, while proportion of perennial weeds increased as the seeding date was delayed. In particular, weed dorminance varied marketly with seeding date. The Simpson's indices were 0.736 on April 20, 0.261 on May 10 and 0.281 on May 30, respectively.

• Korean Journal of Weed Science
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• v.2 no.1
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• pp.31-40
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• 1982

For the effective control of weeds in mechanically transplanted paddy field weeding effects of naproanide ${\alpha}$-(${\beta}$-naphthoxy) propion anilide], pyrazolate [4-2, 4-dichlorobenzoyl)-1, 3-dimethyl pyrazol-5-yl-p-tolune sulphanate], chlormethoxynil (2, 4-dichloro-phenyl-4-nitro-3-methoxy phenyl ether), SL-49 [1-3dimethyl-4(2, 4dichlorobenzoyl)-5-phenacyloxy pyrazole], ACN (3-chloro-2-amino-l, 4-naphthoquinone) either alone or in combination with butachlor (2-chlor-2, 6-diethyl-N-buthoxymethyl acetanilide) were compared. Pyrazolate and SL-49 were most effective for the control of Sagittaria pygmaea MIQ. and Potomogeton distinctus A. BENN. including most annual weeds. Weeding effect of butachlor alone was very high for annuals, good for Cyperus serotinus ROTTB. and poor for S. pygmaea and P. distinctus. But the weeding effect of the combination of butachlor and pyrazolate was stronger than that of butachlor alone and therefore this mixture was effective for S. pygmaea, P. distinctus and C. serotinus including all the annual weeds. The combination of butachlor and SL-49 showed the same tendency as the combination of butachlor and pyrazolate. Naproanilide was not effective for the control of Echinochlor crusgalli P. BEAUV and less effective for Monochoria vaginalis PRESL, but excellent for S. pygmaea. By mixing butachlor with naproanilide weeding, spectrum for annuals and S. pygmaea was much increased by that for P. distinctus and C. serotinus was not satisfactory. ACN was not satisfactory for the control of all the tested weeds but the weeding effect was increased in general by mixing with butachlor. Chlormethoxynil was excellent for the control of annual weeds but it has no effect on C. serotinus, S. pygmaea and P. distinctus showing some initial controling effect but these weeds regrew afterwards. The weeding activity of ACN increased in combination with butachlor and the residual activity was stronger than that of ACN alone. A light crop injury was found at the initial period after treatments in all treated plots. The yield from all treated plots except those from plots treated with ACN, butachlor and naproanilide were not significantly different from the band weeded plot.

• Weed & Turfgrass Science
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• v.3 no.4
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• pp.323-328
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• 2014

This study was conducted to find out the effects of aerial application by unmanned helicopter (AAUH) on controlling weeds under water-seeded rice cultivation. Foliar herbicide (bentazone sodium + fenoxaprop-P-ethyl) was applied with diluted 8-times (standard concentration pest control) as AAUH. Foliar herbicide treatment with standard and two times amount were little damage, but with more than three times amount showed great damage in rice growth. Six annual and two perennial weeds were major weeds occurred in the experimental paddy field. On foliar herbicide treatment 25 days after direct seeding, AAUH showed high control values against weeds (96.3% for annual weeds and 99.8% for perennial weeds). There was no significant difference in weed control values between AAUH and conventional application. There was no spray injury against rice plants with aerial application. In the experiment for good spray timing (15, 20 and 25 days after direct seeding) 15 days showed highest weed control values with 98.5% to annual weeds and 99.8% to perennial weeds and no spray injury.

• Korean Journal of Weed Science
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• v.6 no.1
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• pp.85-96
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• 1986

From the two differently located orchards (even-site with adult tree and slope-site with young tree), weed emergence and the effect of various orchard herbicides on them were comparatively experimented. Weed emergence was assessed in emergence frequency, biomass, relative frequency, and herbicide responses were checked with the variarions in the above weed emergence characters and the weeding values. Herbicides applied were paraquat, glyphosate, oxyfluorfen, napropamide and ustinex using the recommended rates, respectively. Weeds emerged were 7 life-forms, 23 families and 45 species. Among other families, weeds Umbelliferae, Commelinaceae, Gramineae and Polygonaceae couldn't classified in any similarly correlated cluster. However, according to "1-Q mode cluster analysis" of each herbicide performances, "paraquat or glyphosate" with "napropamide or oxyfluorfen" were selected as the most unrelated herbicide pairs expecting the best combination value in mixture model, respectively.

• Weed & Turfgrass Science
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• v.5 no.1
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• pp.1-4
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• 2016

The Rural Development Administration of Korea conducted a series of surveys of paddy weeds from 1971 to 2013 in approximately 10-year cycles and the results have been used for the efficient weed management of paddy fields. In 1971, annual weeds such as Rotala indica, Eleocharis acicularis f. longiseta, and Monochoria vaginalis were dominant. In 1981, the population of Echinochloa species decreased whereas broadleaf weeds such as M. vaginalis, Sagittaria pygmaea, and S. trifolia were dominant. In 1991, perennial weeds such as Eleocharis kuroguwai, S. pygmaea, and S. trifolia were dominant over annual weeds. In 2000, M. vaginalis was the most abundant species, followed by E. kuroguwai, Echinochloa species, and S. trifolia. In 2013, herbicide-resistant Echinochloa species and M. vaginalis were most dominant, followed by E. kuroguwai, Scirpus juncoides, and S. trifolia. It has been predicted that the prevalence of Echinochloa species will continue to increase and that perennial weeds will be more abundant than annual ones in the near future. The occurrence of herbicide-resistant weeds and exotic weeds will also increase due to global warming and changes in agricultural patterns.

• Korean Journal of Weed Science
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• v.15 no.3
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• pp.232-237
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• 1995

Effect of azimsulfuron {1-(4,6-dimethoxypyrimidin-2-yl)-3-[1-methyl-4-(2-methyl-2H-tetrazol-5-yl) pyrazol-5-ylsulfonl]urea} combined with eight annual herbicides on shoot and root growth of rice (Oryza sativa L.) and barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.] was investigated. Annual herbicides used were four thiocarbamates (dimepiperate, molinate, esprocarb, and thiobencarb), two acetanilides (butachlor and pretilachlor), one urea (dymron), and one oxadiazole (oxadiazon) herbicide. Growth inhibition in rice shoot was greater with azimsulfuron mixed with the annual herbicides than with azimsulfuron only. The azimsulfuron mixtures did not bring about decrease in growth inhibition of rice shoot. However, safening effect in root growth of rice was obtained when dimepiperate, molinate and dymron were combined with greater than 10ppm of azimsulfuron. Greater inhibition in shoot and root growth of rice occurred with straight chain hydrocarbon substitute such as esprocarb and thiobencarb than with cyclohydrocarbon substitute such as dimepiperate and molinate. Application of the azimsulfuron mixtures resulted in increase. in growth inhibition of shoot and root growth of barnyardgrass as compared with when azimsulfuron only was applied.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.2
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• pp.199-206
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• 1996

Vegetation succession and changes in soil chemical properties were investigated in 10 abandoned rice fields in Kyunggi Province in 1995. Annual weeds were dominant at the first year of abandonment, later on Perennial weeds became dominant as the period of abandonment progressed. The number of Salicaceae(willow family) increased rapidly as the abandonment period further progressed. In cultivated fields, soil pH and cation contents are slightly higher in subsurface layer than surface layer. In abandoned fields, however, pH of surface layer was getting higher than subsurface soil layer with the lapse of time. Similar trends were observed in case of exchangeable Ca and Mg contents.

• Korean Journal of Agricultural and Forest Meteorology
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• v.15 no.2
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• pp.67-75
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• 2013

The purpose of this study was to collect the basic data on establishing the conservation plan for the domestic wetland through flora and life form analysis at Junam wetland. The vascular plants were recorded as 222 taxa; 58 families, 167 genera, 200 species, 3 subspecies, 1 forma and 18 varieties. Among 8 life forms, Therophytes (Th), Hemicryptophytes (H) and Hydrophytes (HH) showed high percentage, and these species comprised 71.1% of the whole flora at Junam wetland. One taxa (Euryale ferox) rare plants designated by Korea Forest Service were observed. The naturalized plants were 38 taxa including Fallopia dumetora, Oenothera odorata, Ambrosia artemisiifolia var. elatior and so forth, and naturalized ratio was 17.1%. The naturalized made up about 45 percent of the species composition. The specific plants by floristic region were 13 taxa including Euryale ferox., Hydrocharis dubia, Prunus davidiana and so forth.

• Korean Journal of Weed Science
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• v.18 no.4
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• pp.286-294
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• 1998

This study was carried out to evaluate the interaction effect between molinate(S-ethyl N,N-hexamethylene-thiocarbamate) and simetryn(N,N'-diethyl-6-(methythio)-1,3,5-triazine-2,4-diamine) on weed bioefficacy and rice phytotoxicity in green house and paddy field. Combined application of molinate and simetryn showed synergistic herbicidal effect to Echinochloa crus-galli and additive herbicidal effect to Bidens tripartita, However, it showed synergistic phytotoxicity to rice. Combined application of molinate and simetryn reduced the flooding period desirable for controlling Echinochloa crus-galli by about 2~4days as compared to single application of molinate. It was concluded that the optimum combination of molinate and simetryn was 150g and 9g to 18g a.i./10a, respectively in viewpoint of bioefficacy and phytotoxicity.

• Korean Journal of Weed Science
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• v.31 no.3
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• pp.308-312
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• 2011

A new paddy field herbicide, metazosulfuron granule is an herbicide for controlling annual and perennial weeds occurring in machinery transplanting paddy field. It is recommended to apply $30kg\;ha^{-1}$ 15 days after transplanting. As a result of preliminary tests, it could control seven annual species such as Echinochloa crus-galli, Bidens tripartita, Ludwigia prostrata, Monochoria vaginalis var. plantaginea, etc. and four perennial species including Cyperus serotinus, Sagittaria trifolia, Eleocharis kuroguwai, and Scirpus juncoides. Monochoria vaginalis var. plantaginea, S. trifolia and S. juncoides resistant to sulfonylurea- herbicides were also controlled. Because application timing of the herbicide is wide, it is very efficient to control the spraying timing by users. Phytotoxicity of rice cultivars was not observed, and the impact on the environment is very limited.